Polyphase power distribution and monitoring apparatus

ABSTRACT

A polyphase power distribution and monitoring apparatus having sets of outputs for each phase of power and monitors for each phase of power disposed in the housing. Each monitor provides a visible display of current for an associated phase of power and an audible alarm for each phase of power if the current exceeds a predetermined value or falls below a predetermined value. In three-phase wye power systems, the apparatus preferably includes a neutral line monitor, including a neutral line current display and audio alarm, for the neutral line of the wye power circuit. The apparatus preferably is lightweight, elongated, portable, and mountable to the side of an electronic equipment rack. It may also include additional power monitoring systems such as network power monitoring tools for remotely monitoring the apparatus.

FIELD OF THE INVENTION

The present invention relates to power distribution apparatus for thedistribution of polyphase alternating current. More particularly, thepresent invention relates to apparatus for distributing polyphasealternating current and monitoring information relating to polyphasepower distributable by the apparatus.

BACKGROUND

Electric current that reverses periodically, usually many times persecond, is called “alternating current.” In most public or commercialpower distribution networks, electrical current is delivered to acustomer or user as alternating current.

Electric current is induced to reverse or alternate periodically by avoltage that reverses or alternates periodically. One complete voltageperiod, with accompanying current flow in one direction and then theother, is called a cycle. In the United States, 60 cycles per second(also referred to as “60 Hz”) is the standard frequency of alternatingcurrent in most environments. In Europe, 50 Hz is the standard.

Typically, the graphical form of the level of alternating voltage over aperiod or cycle is generally sinusoidal. This is because the nearsinusoidal form is relatively easy, economical, and efficient togenerate, deliver, and utilize.

Power distributed to small businesses or homes is commonly “singlephase” or “dual phase” power. In a single phase system, a singlealternating voltage is distributed through a two-line connection. In adual phase system, two alternating voltages are distributed through atleast three lines: one neutral line and one other line for each of thetwo alternating voltages. The time that the voltage on one of theselines is zero and the time that voltage on the second of these lines iszero are separated by a time period equivalent to the time lapse of onehalf of one cycle. The two voltages are separated in time by a “phasedifference”—that is, the sinusoidal form of the voltage on one lineleads or lags the sinusoidal form of the voltage on the other line bythe amount of the phase differential. The effective voltage between thefirst phase line and the second phase line is therefore significantlygreater that the effective voltage between each of the phase lines andthe neutral line. As a result, a three-line, two-phase system mayprovide, for example, 120 volts in a phase-to-neutral line circuit and240 volts in a phase-to-phase line circuit.

In large commercial and industrial applications, three phase systemshave long been common. In three phase systems, each voltage cycle oneach phase line is 120 degrees, or ⅓ of a period, out of phase with thevoltage cycle on each of the other two phase lines. Three phase systemsare used in large commercial and industrial applications becausethree-phase equipment is smaller in size, weighs less, and is moreefficient than single or dual phase equipment. Although three phasecircuits are somewhat more complex than single or dual phase circuits,they too weigh less than single phase circuitry for the same loadssupported by the circuitry. Three phase circuits also can provide a widerange of voltages and can be used for single or dual phase loads.

Three phase circuits power is generated by circuits in either of twoconfigurations: (i) a “delta”; or (ii) a “wye” configuration. If one endof each of the legs of a three-phase circuit are centrally connected ata common point and the other ends are connected to three phase lines(one line for each phase), the configuration is called a wye or “Y”connection. If the legs of the three phase circuits are connectedinstead in series to form a closed loop, with one phase line connectedto each junction of two adjacent legs, the configuration is called adelta or “Δ.”

One reason that three phase circuits are more complex than typicalsingle phase and dual phase circuits is the need to maintain at leastsomewhat balanced loads among each of the three phases. One indicator ofimbalance is the level of current flowing through each phase line. Ifthe level of current flowing through a phase line is different than thatflowing through a different phase line, the load is obviouslyunbalanced. In a wye connected system, imbalance can also be indicatedby current flowing through the neutral line, and this situation canarise when the amount of current flowing through each phase is identicalin amplitude but differing in phase due to the nature of the loadsserved by the lines. Imbalance between the loads can result in damage tothe three phase system, can cause excessive wear of components in thesystem such as the three-phase generator, and can be difficult andcostly to correct.

For example, in many industrial three-phase applications, such ascomputer and communications network applications, three-phase power issupplied to racks of equipment. One common prior art system providesthree-phase power to one or more racks via a four line input, providinga line for each voltage phase and a common ground or neutral line. Anelongated power distribution plug strip connects to the input anddistributes power of differing phases to a plurality of plug stripoutputs for the phase. The three-phase plug strip typically providesthree branches of outputs, one branch for each phase of power providedby the three-phase plug strip. This plug strip is mountable on oradjacent to a given equipment rack in order to supply three branchessingle phase power (with each such branch derived from the three-phasepower intput) to the rack or other equipment in the vicinity.

In order to help ensure that each branch of outputs supplies acumulative load that is balanced as compared to the cumulative loadserved by the other branches of outputs, this prior art three-phaseplugstrip has included a single current display visible to an operatoralong the face of the plugstrip in which the outputs are also mounted.The installer or on-site operator or user (collectively the “operator”)can use this display to determine the total amount of current flowingthrough each branch of outputs by physically pushing an associatedbutton mounted on the plugstrip housing. This causes the display tocycle through numerical indications of the total current for eachdiffering phase branch of output. If the current indicated for one phaseset (branch) is different than that for another current indicated for adifferent phase set of outputs, the loads are unbalanced. When thisdifference becomes too great, the operator is thereby alerted to theneed to take corrective action to correct the imbalance.

The applicant has discovered that another problem with this type ofprior art system is that it requires the operator to take the time andeffort to stop whatever the operator may be doing, turn attention to theplugstrip, and press the display button on the plugstrip to cyclethrough and observe the current indicators for the various phases. Inthe case of a wye connected system, this type of prior art alsotypically has not provided for display or ready determination of thelevel of current flowing through the neutral line. As a result, users ofsuch prior art systems may not be receive any indication of imbalancewhen current flows through the neutral line, indicating an imbalance infact, but the current level flowing through each phase provides no suchindication.

Prior art power supply systems have also included other tools to helpdetermine imbalance among loads supplied by three-phase systems. Onesuch system in common use includes a remote power management featurethat remotely monitors the power supply plugstrip through a networkconnection between the plugstrip and a computer with an associatedcomputer screen. A user at the computer screen can observe informationabout each phase of power and whether there is an imbalance betweenphases.

This type of network system, however, requires the user to have accessto a computer screen in order to observe information about the level ofimbalance, and this type of computer screen is often unavailable or isotherwise inconvenient to inspect at the on-site location of theplugstrip itself. At this location, for example, there may be no spaceavailable for a computer screen much less one networked to theplugstrip, and during installation of the plugstrip, the installer mayhave little time or ability to set-up or inspect a computer screen.

BRIEF SUMMARY OF THE INVENTION

The applicant has invented a polyphase alternating current powerdistribution apparatus providing a plurality of power informationmonitors secured to the housing of the apparatus. Preferably, theapparatus includes a monitor for each phase of power distributed by theapparatus and for the neutral line in the case of a polyphase systemutilizing a neutral line, such as a wye-connected system.

Most preferably, the power information monitors each display the currentflowing in an associated phase line or neutral line as applicable. Theinformation monitors also may issue an audible alarm if the current flowin the associated line exceeds an adjustable predetermined level.

Preferably, the housing for the apparatus is elongated, phase poweroutputs are mounted in clusters along an elongated side of the housing,and for each such cluster, the power information monitor is mountedadjacent the cluster in an elongated side of the housing. The apparatusmay be most advantageously mounted vertically adjacent or within avertical side of an electrical or electronic equipment rack.

Preferably, each of the power information monitors is readily viewableby a user during installation or use of the apparatus. Preferably, theapparatus readily provides information and associated sensory alarms,such as audio alarms, indicative of possible load balance or imbalancebetween the power phases distributed by the apparatus.

In the preferred apparatus, additional power monitoring features alsocan be provided, including remote power management and monitoring,audible alarms, or fuses. Most preferably, the power distributionapparatus is relatively lightweight, economical, and easy tomanufacture, install, and use.

There are additional novel and inventive aspects of the preferredembodiments. They will become apparent as the specification proceeds. Inthis regard, it is to be understood that the scope of the invention isto be measured by the claims as issued and not whether any given subjectmatter provides any or all features recited this Brief Summary of theInvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present invention is shown in theaccompanying drawing in which:

FIG. 1 is an isometric view of the applicant's preferred three-phasedelta power distribution and monitoring apparatus;

FIG. 2 is an isometric view of the applicant's preferred three-phase wyepower distribution and monitoring apparatus;

FIG. 3 is schematic wiring diagram of the three-phase wye powerdistribution and monitoring apparatus of FIG. 2; and

FIG. 4 is a schematic wiring diagram of the three-phase delta powerdistribution and monitoring apparatus of FIG. 1.

In the following specification, certain spatially identifying terms areused, such as the term “vertical.” It is to understood that thisterminology is used to identify the orientation of the element withrespect to electrical or electronic equipment racks, which typically aremounted vertically with respect to a floor in room. These types of termsdo not by themselves, however, require any absolute orientation inspace.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, the preferred three-phase delta powerdistribution and monitoring apparatus, generally 10, has an elongatedaluminum housing 12, a three-phase power input cord 14 penetrating oneend 16 of the housing 12, three sets of power output plug receptacles,generally 18, 20, and 22 on an elongated faceplate side 24 of thehousing 12, and, adjacent each set of power output plug receptacles 18,20, and 22, an associated phase line current display 26, 28, 30respectively. In the preferred embodiment of FIG. 1, the housing 12measures 35.5 inches long, by 4.5 inches wide, by 1.75 inches deep.

The entire power distribution and monitoring apparatus 10 weighstwenty-one to twenty-three lbs. and is easily transported and verticallymounted on an associated RETMA electronic equipment rack (not shown). Inthe preferred embodiment, the housing 10 can include fasteners andfastener passages (not shown) in order to secure the housing 10 to aRETMA rack.

Referring now to FIG. 4, the three-phase power input cord 14 has fourlines: line A, line B, and line C, and power ground 32. These four linesA,B,C, 32 all terminate in a terminal block 34. The power ground 32 is,in turn, grounded 35 to the housing or enclosure 12 (not shown in FIG.4).

Three power supplies 36, 38, 40 are connected to the terminal block 34.The power supply for phase A (36) is connected through terminal block 34to line A and line B. The power supply for phase B (38) is connectedthrough terminal block 34 to Line B and Line C. In turn, the powersupply for phase C (40) is connected through terminal block 34 to Line Cand Line A. The phase A power supply 36 therefore receives phase A tophase B voltage; the phase B power supply 38 receives phase B to phase Cvoltage; and the phase C power supply 40 receives phase C to phase Avoltage.

Each power supply, e.g., A (36), provides its received phase-to-phasevoltage to two associated sub-set or branches 42, 44 of seven poweroutput plug receptacles, e.g., 46. Each such branch, e.g., 42, includesa fuse, e.g., 48, in the line to protect the branch from shorts andover-current conditions at or through associated branch outputs oroutlets, e.g., 46. Each such outlet, e.g., 46, includes an output line50 grounded to the housing 12 (not shown in FIG. 4). A standardelectrical supply input plug (not shown) can then be inserted in any ofthe output receptacles, e.g., 46, and thereby receive associated phasepower, e.g., A, from power supply 36 supporting the output receptacle46.

Each power supply, e.g., A (36), includes circuitry that convertsreceived phase power to 5 volt direct current (“VDC”) and distributesthe 5 VDC to an associated digital display module 26. The power supply36 circuitry also (i) senses the magnitude of the total phase A currentflowing through the power supply 36 to the fourteen power outputreceptacles, e.g., 46, supported by the power supply 36, (ii) convertsthe total phase A current magnitude to an 0-5 VDC analog signalrepresenting the RMS of such total phase A current magnitude, and (iii)transmits the analog signal to the digital display module 26.

The digital display module 26 thereby displays the RMS phase A to phaseB current value so that this value is visible to a user viewing thedisplay module 26 on the housing 12. The digital display module 26 alsoincludes an audio alarm and generates an audible alarm when the currentvalue exceeds a preset level. In the preferred embodiment, the audioalarm is set to trigger, via jumpers set at the factory, at at 20 or 30amps and for overload, with a differing audio alarm at 31 amps.

With reference now to FIG. 2, the preferred three-phase wye powerdistribution and monitoring apparatus, generally 60, is configured muchlike the delta power distribution and monitoring apparatus of FIG. 1.The wye apparatus 60, however, also includes a neutral line currentdisplay and alarm 62 mounted in the elongated faceplate 64 on thehousing or enclosure 66 and, as shown in FIG. 3, includes a neutralpower supply 68, a three-phase wye power input cord, 69, and differingwiring among these components and the three power supplies: A (70), B(72), and C (74).

In this wye embodiment 60, the power input cord 69 has phase A, B, and Clines, a neutral line 71, and ground line 73. The ground line 73 isgrounded to the housing through the terminal block 75, and the neutralline 71 is connected through the terminal block 75 to the neutral powersupply 68. Power supply A (70) is connected through terminal block 75 toline A and, through the neutral power supply 68, to the neutral line 71.Power supply B (72) is connected through terminal block 75 to Line Band, through the neutral power supply 68, to the neutral line 71. Inturn, power supply C (74) is connected through terminal block 75 to LineC and, through the neutral power supply 68, to the neutral line 71.Power supply A (70) therefore receives phase A to neutral voltage; powersupply B (72) receives phase B to neutral voltage; and power supply C(74) receives phase C to neutral voltage.

The neutral power supply 68 also is connected through the terminal block75 to the phase A line. The neutral power supply 68 includes circuitrythat converts received phase A power to 5 volt direct current (“VDC”)and distributes the 5 VDC to an associated neutral line digital displaymodule 62. The power supply 68 circuitry also (i) senses the magnitudeof the total neutral line current if any net neutral line current exists(in a perfectly balanced system, there is no net current in the neutralline), (ii) converts the neutral line current magnitude to a 0-5 VDCanalog signal representing the RMS of such neutral current magnitude,and (iii) transmits the analog signal to the neutral line digitaldisplay module 62.

The digital display module 62 thereby displays the neutral line currentvalue so that this value is visible to a user viewing the neutral linedisplay module 62 on the housing faceplate 64. The neutral line digitaldisplay module 62 also includes an audio alarm and generates an audiblealarm when the current value exceeds a preset level, as describe above.Alternatively or in addition, the digital display module 62 can includea differing sensory alarm when the current exceeds or falls below apredetermined level or range of values.

In the preferred embodiments, each power supply, e.g., 70, includescurrent distribution lines, a module for converting alternating currentto direct current, a current sensing transducer, and a processor forconverting analog output from the current sensing transducer to adigital output. Each digital display module, e.g., 62, includes a twodigit LED indicator, an alarm buzzer, and a processor that generates analarm when the current exceeds the factor pre-set level as explainedabove. These power supply 70 and digital display module 62 componentsare assembled in a fashion well known to those skilled in the art.

Both the delta and the wye power distribution and monitoring apparatusof FIGS. 1-4 may be adapted to provide or be implemented in conjunctionwith remote power management and reporting systems. Apparatus andsystems for doing so are disclosed in references such as: (i) U.S. Pat.No. 5,506,573, entitled Remote Sensor and Method for Detecting theOn/Off Status of An Automatically Controlled Appliance, issued to Ewinget al. on Apr. 9, 1996; (ii) U.S. Pat. No. 5,949,974, entitled Systemfor Reading the Status and for Controlling the Power Supplies ofAppliances Connected to Computer Networks, issued to Ewing et al. onSep. 7, 1999; and (iii) the applicant's U.S. co-pending applicationentitled “Network Remote Power Management Outlet Strip,” Ser. No.10/313,314, filed Dec. 6, 2002, the disclosures of all of whichreferences are hereby incorporated herein by reference in theirentireties.

It can thus be seen that the applicant has provided a polyphase (and inthe preferred embodiments, three-phase) power distribution andmonitoring apparatus that preferably provide a clear but self-contained,unobtrusive, and space-saving power monitor for each of multiple powerphases and, if desired, the neutral line in the case of a wye connectedthree-phase power supply system. In this regard, in this specificationthe term “monitor” means a current display or other sensory indicator,such as an audible or other sensory alarm, mountable on or to thehousing of the power distribution and monitoring apparatus. Thepreferred embodiments also are relatively portable, lightweight, slim,economical, and easy to manufacture, install, use, and maneuver.

One skilled in the art may readily adapt other polyphase power supplysystems to provide novel features of the types disclosed herein, suchas, for example, on-site current displays and alarms for each phase orother line in the power supply system. The present invention istherefore not necessarily limited to, for example, three-phase systemsby the detailed description of preferred embodiments set forth above.

1-26. (canceled)
 27. A polyphase alternating current power distributionapparatus comprising, in combination: a power distribution housing; apolyphase power input disposed in the power distribution housing; aplurality of power outputs disposed in the power distribution housing; aplurality of separate power information visual display sections disposedin the power distribution housing; means for distributing a first powerphase received by the polyphase power input to at least a first outputof the plurality of power outputs; means for distributing a second powerphase received by the polyphase power input to at least a second outputof the plurality of power outputs; means for reporting, at the powerdistribution apparatus, power information regarding the first powerphase distributed by at least the first output with at least a firstpower information visual display section of the plurality of separatepower information visual display sections; and means for reporting, atthe power distribution apparatus, power information regarding the secondpower phase distributed by at least the second power output with atleast a second power information visual display section of the pluralityof separate power information visual display sections while reportingpower information regarding the first power phase with the first powerinformation visual display section.
 28. The polyphase alternatingcurrent power distribution apparatus of claim 27, wherein the means forreporting power information regarding the first power phase comprisesmeans for determining current of the first power phase.
 29. Thepolyphase alternating current power distribution apparatus of claim 27,wherein the means for reporting power information regarding the secondpower phase comprises means for determining current of the second powerphase.
 30. The polyphase alternating current power distributionapparatus of claim 27, further comprising, means for distributing athird power phase received by the polyphase power input with at least athird output of the plurality of power outputs.
 31. The polyphasealternating current power distribution apparatus of claim 30, furthercomprising, means for reporting, at the power distribution apparatus,power information regarding the third power phase distributed by atleast the third power output with at least a third power informationvisual display section of the plurality of separate power informationvisual display sections while reporting power information regarding thefirst and second power phases with the first and second powerinformation visual display sections respectively.
 32. The polyphasealternating current power distribution apparatus of claim 31, whereinthe means for reporting power information regarding the third powerphase comprises means for determining current of the third power phase.33. The polyphase alternating current power distribution apparatus ofclaim 27, further comprising, means for providing a sensory alarm,whereby a human in the vicinity of the power distribution apparatus mayreceive sensory stimulation from the sensory alarm.
 34. A polyphasepower distribution and monitoring apparatus comprising, in combination:a power distribution housing; a plurality of input lines disposed in thepower distribution housing; a power ground disposed in the powerdistribution housing; a plurality of power supplies disposed in thepower distribution housing; a plurality of output plug receptaclesdisposed in the power distribution housing; a visual display moduledisposed in the power distribution housing; means for transmittingthrough each of the plurality of power supplies phase power from atleast one of the plurality of input lines and to at least one of theplurality of output plug receptacles; means for sensing in each of theplurality of power supplies a magnitude of the phase power flowingthrough the power supply; means for converting in each of the pluralityof power supplies the magnitude of the phase power into a correspondingsignal representing the magnitude of the phase power flowing through thepower supply; means for transmitting the signals to the visual displaymodule, wherein the visual display module comprises a plurality ofseparate visual displays; and means for reporting, with the plurality ofseparate visual displays, the signals each representing the magnitude ofthe phase power flowing through the corresponding power supply, thereporting of one of the plurality of separate visual displaysoverlapping with reporting of at least one other of the plurality ofseparate visual displays.
 35. The polyphase power distribution andmonitoring apparatus of claim 34, further comprising means forgenerating an alarm when the signal meets at least one specifiedcriteria.
 36. The polyphase power distribution and monitoring apparatusof claim 34, wherein the means for sensing comprises a current-sensingtransducer.
 37. The polyphase power distribution and monitoringapparatus of claim 36, further comprising means for converting an analogoutput from the current-sensing transducer to a digital output to bedisplayed on at least one of the plurality of separate visual displays.